Basics
Description
Degenerative disease of the acromioclavicular (AC) joint, often resulting in shoulder pain
- Acute: usually due to traumatic AC separation-can lead to chronic osteoarthritis (OA) over time
- Chronic: due to repetitive strain and degeneration over time (classic form of AC arthritis)
- Typically occurs as OA in middle-aged adults
- Caused by mechanical friction of the articular surfaces of the distal clavicle and acromion
Epidemiology
- Acute
- More common in adolescents and young adults who are more prone to muscle strains and traumatic injuries (AC separation)
- Due to trauma (not chronic degeneration)
- Less common form of AC arthritis/pain
- Chronic
- Typically affects middle-aged adults (1)
- AC joint normally degenerates over several decades. AC arthritis occurs earlier in life than glenohumeral joint arthritis or other types of OA.
- Second most common shoulder pathology in adults older than age 40 years (following rotator cuff tendinopathies or tears) (2)
- Adhesive capsulitis or frozen shoulder is more common in geriatric patients (2).
Incidence
- 15/1,000 patients primary care patients have shoulder pain annually in primary care setting (1).
- 1% of patients present to primary care physicians (PCPs) with new-onset shoulder pain annually.
- Predominant age: 40s
- No predominant sex
Prevalence
- ~16% of musculoskeletal (MSK) complaints seen in PCP office are due to shoulder pain: second only to back pain (1)
- ~20% of Americans have shoulder pain at some point.
- 24% of patients seeing PCP with shoulder pain have AC arthritis; 77% with >1 etiology of shoulder pain (2).
- 5% of Americans experience AC arthritis during their lifetime.
Etiology and Pathophysiology
- Result of repeated movements or trauma that wears away fibrocartilaginous disk between the acromion and clavicle
- Articular disk can begin to break down by 2nd decade of life, although often not symptomatic until years later.
- History of AC separation contributes to AC joint arthritis.
- Inflammation from rotator cuff pathology can impact AC joint mechanics, contributing to arthritis.
Risk Factors
- History of trauma or contact sports, history of overhead sports (baseball, swimming), active weight lifting (bench or military press)
- Rheumatoid arthritis (RA) or other inflammatory arthritides
General Prevention
- Avoid highly repetitive motions that involve the AC joint (encourage proper technique for those who participate regularly in overhead/cross-body activities such as golf, swimming, and tennis).
- For throwing sports such as baseball, encourage pitch count in young athletes.
- For weight lifters with heavy overhead lifting, encourage use of a wider grip (3).
Commonly Associated Conditions
- Rotator cuff disorders (often concurrent)
- RA (consider with bilateral AC arthritis)
Diagnosis
History
- History of trauma (prior AC separation)
- History of overhead sports such as baseball, weight lifting, tennis, and swimming
- Family or personal history of inflammatory disease or arthritis
- Pain typically located at top of shoulder
- Pain worse with cross-arm movements or with internal rotation (1)
- Pain may wake patients from sleep, particularly when rolling on affected shoulder.
Physical Exam
- Inspection
- Presence of step-off at AC joint (suggests AC separation)
- Palpation
- Anterior/superior pain localized to AC joint
- Tender to palpation (TTP) at AC joint 96% sensitivity (4)[A]
- Palpable osteophyte (not common)
- Range of motion
- Usually preserved but can have pain or hesitation with adduction/cross-body test
- Provocative tests
- Cross-body adduction: 77% sensitivity, 79% specificity, and +3.5 LR for AC joint OA (1)[A]
- Paxinos sign (press the acromion and clavicle simultaneously to compress the AC joint space): less sensitive than other tests (5)
- Bell-van Riet test: cross-body adduction test with attempted elevation against resistance. Sensitivity is 98% (5)[A].
- O'Brien test (upper extremity in 90 degrees of shoulder flexion and 10 degrees of horizontal adduction): Patient internally rotates shoulder and pronates forearm. Physician provides distal pressure as patient actively raises upper extremity. Repeat in neutral position of shoulder/forearm. Pain/clicking of AC joint with first maneuver (not second) suggests AC pathology sensitivity of up to 83%.
Differential Diagnosis
- Rotator cuff disorders (tendinopathy, partial and complete tear)
- Adhesive capsulitis (more common in older patients or patients with diabetes)
- Shoulder instability (history of dislocation)
- Shoulder arthritis (glenohumeral joint)
- Biceps tendonitis
- Referred pain (extrinsic cause such as subdiaphragmatic irritation): less likely. Usually correlates with systemic symptoms
Diagnostic Tests & Interpretation
- History and physical exam provide an accurate diagnosis in most cases.
- TTP plus positive Bell-van Riet or cross-body test is indicative of AC arthritis.
- Radiographs may be nonspecific. Often have abnormal findings in asymptomatic patients due to natural joint degeneration (4).
- Zanca cephalic tilt for better AC visualization
- Can see distal clavicle lysis or elevated distal clavicle (1)[A]
- Sclerosis of lateral head of acromion or hypertrophic spurs also common
- Magnetic resonance imaging (MRI): imaging of choice for rotator cuff tear or tendinopathy
Follow-Up Tests & Special Considerations
N/A (See "Treatment" below.)
Diagnostic Procedures/Other
AC joint injection with lidocaine: used to isolate AC arthritis
- AC joint injection much more reliable with ultrasound guidance (4)
Treatment
- Most patients respond well to combination of activity modification, physical therapy, medications, and steroid injections (3)[B].
- Activity modification
- Decrease cross-body motions (golf, baseball), overhead activities (swimming, shoulder press), or bench press.
- Widen grip with weight lifting; help alleviate tension on AC joint.
- Physical therapy
- Decrease pain and improve function.
- Less effective than when used for rotator cuff pathologies (3)
Medication
First Line
- Acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs). Not many trials comparing two classes.
- Ibuprofen
- Do not exceed 2,400 mg PO daily (800 mg t.i.d.).
- Caution in geriatric patients, history of gastrointestinal (GI) bleed or ulcer, or if renal dysfunction
- Acetaminophen
- Do not exceed 3,000 mg PO daily (1,000 mg t.i.d.).
- Caution in patients with liver dysfunction, heavy ethanol (EtOH) use, other drug use
- Topical NSAID use: not as well studied
Second Line
- Opiates are typically not necessary for management of AC arthritis.
- Often given with acute pain in setting of AC separation (3)
- Corticosteroid injection
- Provides acute pain relief. Can also be used when symptoms do not improve with conservative therapy.
- Good evidence for short-term pain relief. Long-term outcomes not significantly different (4)[B].
- Joint space small and difficult to inject; blind technique leads to correct needle placement 37% of the time (4).
- 25-gauge needle, 1-mL steroid or less, 1-mL lidocaine. Needle advances ~1 cm under skin unless patient is very muscular or obese.
- Acute adverse effects of injections (rare): infection, vagal response, anaphylaxis, and high blood sugar levels (4)
- Chronic adverse effects: not typical in AC injection. Typically included chronic weakening or destruction of soft tissue structures surrounding the joint with repeated injections (4).
Issues for Referral
If patient fails to improve, does not regain adequate shoulder function, or has poorly controlled pain with conservative therapy, consider surgical evaluation (3,4).
Additional Therapies
- Acupuncture: limited evidence for long-term effectiveness
- Ultrasound physiotherapy: not effective
- Glucosamine and chondroitin: mixed evidence
Surgery
Indicated only if no improvement with conservative measures after minimum of 3 months
- Subacromial decompression with distal clavicular resection
- AC joint fills with scar tissue, allowing for more normal movement.
Ongoing Care
Prognosis
- Chronic degenerative condition that is likely to progress over time
- Activity modification is the best way to slow progression.
- Surgery can be definitive treatment.
References
1.Burbank KM, Stevenson JH, Czarnecki GR, et al. Chronic shoulder pain: part 1. Evaluation and diagnosis. Am Fam Physician. 2008;77(4):4530-460.
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2.House J, Mooradian A. Evaluation and management of shoulder pain in primary care clinics. South Med J. 2010;103(11):1129-1135.
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3.Burbank KM, Stevenson JH, Czarnecki GR, et al. Chronic shoulder pain: part II. Treatment. Am Fam Physician. 2008;77(4):493-497.
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4.Codsi M. The painful shoulder: when to inject and when to refer. Cleve Clin J Med. 2007;74(7):473-488.
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5.van Riet RP, Bell SN. Clinical evaluation of acromioclavicular joint pathology: sensitivity of a new test. J Shoulder Elbow Surg. 2011;20(1):73-76.
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Codes
ICD09
- 716.91 Arthropathy, unspecified, shoulder region
- 715.31 Osteoarthrosis, localized, not specified whether primary or secondary, shoulder region
- 716.11 Traumatic arthropathy, shoulder region
- 716.81 Other specified arthropathy, shoulder region
- 714.0 Rheumatoid arthritis
- 716.61 Unspecified monoarthritis, shoulder region
ICD10
- M13.819 Other specified arthritis, unspecified shoulder
- M19.019 Primary osteoarthritis, unspecified shoulder
- M12.519 Traumatic arthropathy, unspecified shoulder
- M19.219 Secondary osteoarthritis, unspecified shoulder
- M06.011 Rheumatoid arthritis w/o rheumatoid factor, right shoulder
- M06.012 Rheumatoid arthritis w/o rheumatoid factor, left shoulder
- M06.019 Rheumatoid arthritis w/o rheumatoid factor, unsp shoulder
- M12.511 Traumatic arthropathy, right shoulder
- M12.512 Traumatic arthropathy, left shoulder
- M13.811 Other specified arthritis, right shoulder
- M13.812 Other specified arthritis, left shoulder
- M19.011 Primary osteoarthritis, right shoulder
- M19.012 Primary osteoarthritis, left shoulder
- M19.211 Secondary osteoarthritis, right shoulder
- M19.212 Secondary osteoarthritis, left shoulder
SNOMED
- 429459001 Arthritis of acromioclavicular joint (disorder)
- 239865003 Osteoarthritis of acromioclavicular joint (disorder)
- 201943001 Traumatic arthropathy of acromioclavicular joint (disorder)
- 432733005 Acute degenerative joint disease of shoulder region (disorder)
- 201849003 Localized, secondary osteoarthritis of the shoulder region (disorder)
- 43829003 Chronic osteoarthritis (disorder)
Clinical Pearls
- Chronic shoulder pain is the second leading MSK cause of visits to PCPs. AC joint arthritis is the second most common cause of shoulder pain.
- AC pain in younger patients is typically due to trauma.
- In middle-aged adults, OA is the most common cause of AC pain.
- Provocative tests to diagnose AC arthritis include cross-body adduction and the Bell-van Riet test. The Bell-van Riet test has the highest sensitivity.
- First-line treatment includes activity modification, oral pain medications, and physical therapy.
- Surgery is indicated if there is no improvement with conservative treatment after 3 months.